The Earth’s magnetic field helps preserving our planet’s sliver of life-sustaining atmosphere by deflecting high-energy particles and plasma that are frequently blasted out by the sun. Recently, by analyzing a recurrent radio signal coming from outside our solar system, an international team of astronomers has identified a prospective Earth-sized exoplanet – called YZ Ceti b and located 12 light years away from us – that could also have a magnetic field and may thus potentially harbor life.
“The search for potentially habitable or life-bearing worlds in other solar systems depends in part on being able to determine if rocky, Earth-like exoplanets actually have magnetic fields,” said Joseph Pesce, a program director at the National Radio Astronomy Observatory. “This research shows not only that this particular rocky exoplanet likely has a magnetic field but provides a promising method to find more.”
According to the researchers, the stellar radio waves they detected are most probably generated by the interactions between the magnetic field of YZ Ceti b and a small red dwarf star that it orbits, known as YZ Ceti. Since this exoplanet is so close to its star that it completes a full orbit in only two days, the plasma from the star that careens off the planet’s magnetic “plow” then interacts with the magnetic field of the star itself, generating radio waves strong enough to be detected from Earth.
On Earth, the interaction between “solar weather” – referring to the sun’s high energy particles and occasional huge bursts of plasma – and our planet’s magnetic field can disrupt global telecommunications and short-circuit electronics in satellites and even on the Earth’s surface, while also creating the phenomenon known as aurora borealis, or northern lights. The experts were surprised to discover that, although the interactions between YZ Ceti b and its star also produces an aurora, there was a significant difference: in this case, the aurora was located on the star itself.
“We’re actually seeing the aurora on the star – that’s what this radio emission is,” explained Sebastian Pineda, an astrophysicist at the University of Colorado Boulder who first detected this signal. “There should also be aurora on the planet if it has its own atmosphere.”
Although YZ Ceti b remains the best candidate yet for a rocky exoplanet with a magnetic field, further research is needed to make sure this is the cause of the observed radio signal and, if so, clarify what the presence of a magnetic field on this exoplanet implies for the possibility of its habitability.
The study is published in the journal Nature Astronomy.
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